The synthesis of ent-12-fluoroPGF2 alpha and ent-15-epi-12-fluoroPGF2 alpha will be completed. The minimum effective dose to terminate pregnancy in hamsters will be determined. In addition smooth muscle data will be obtained. The synthesis of 10 Beta-fluoroPGF2 alpha will be completed and submitted for biological evaluation. The synthesis of 10 alpha-fluoroPGF2 alpha will be initiated.